Treatment regimens and clinical intervention are driven by information obtained by ongoing patient monitoring. Current methods for protein biomarker detection are based on well established techniques, including gel electrophoresis and antibody-based detection. Current technologies show outstanding promise for improving the information obtained from patient samples;these benefits can also be coupled with a decrease in the amount of material that has to be collected from the patient. Chief among these emerging methods is quantitative mass spectrometry. Building on reaction monitoring techniques that have been developed to study drug delivery and distribution, assays can be developed to quantify protein biomarkers from complex mixtures, such as blood or urine. The development of these assays relies on selective detection of specific peptides, which are enzymatically cleaved segments of a protein. Peptides are used as a surrogate to quantify their protein of origin. Using a triple quadrupole mass spectrometer, the intact peptide can be filtered out by mass and fragmented by collisions with background gas molecules (e.g. argon);then, selective fragment ions are filtered out for detection. This two-stage mass spectrometry selection enables focused detection of molecules that have the same intact molecular weight and structural fragments, in this case, similar peptide composition and sequence. Coupled with reverse phase liquid chromatography separations, these pairs of intact molecular weight and fragment ion mass, known as transitions, provide three chemical characteristics to isolate the signal of the target molecule from a complex matrix like blood or urine. Quantitative mass spectrometry can be used to measure a large number of protein biomarkers in each sample, enabling evaluation of large panels of clinically relevant targets to be assessed in parallel in the same sample. In this proposal, mass spectrometry assays are developed to detect and quantify immunoglobulins from multiple myeloma patients, which will be compared with the current clinical techniques. In myeloma, malignant plasma cells proliferate in the bone marrow, creating several symptoms in the patient. The most damaging are lesions of the bone, but the large amounts of antibodies produced by these cells can also effect regulation of protein levels in the blood and kidney function. The malignant plasma cells secrete large quantities of immunoglobulins, which serve as biomarkers for disease diagnosis and severity. In the clinic, these proteins are monitored by electrophoresis in blood serum and urine;these measurements are used as part of the system for determining treatment regimens for the patients. Quantitative mass spectrometry methods supplement, and may eventually replace, these current clinical techniques, because they provide more sensitive analysis and more comprehensive information about the condition of the myeloma patient PUBLIC HEALTH RELEVANCE Aim 1: This research will examine improvements in detection of multiple myeloma in blood samples collected from patients. Determination of disease relapse will provide the highest current clinical impact;better sensitivity assays based on newer technology can provide more information to the physician, accurately directing patient treatment. Aim 2: Improvements in sampling the urine of multiple myeloma patients will enable simultaneous assessment of the disease and related kidney damage. Together, these aims will also enable comparison of quantitative mass spectrometry tests to current clinical assays, illustrating the benefits of implementing this new technology in patient care.